Lower incisor changes following non-extraction  orthodontic decompensation in Class III surgical  cases

Nor Nadia Zakaria; Yasmin Kamarudin; Ong Kah Shin; Koo Zi Qing

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Lower incisor changes following non-extraction orthodontic decompensation in Class III surgical cases

Author: Nor Nadia Zakaria ¹ ; Yasmin Kamarudin ¹ ; Ong Kah Shin ² ; Koo Zi Qing ²
Author Information

1. Department of Paediatric Dentistry and Orthodontics, Faculty of Dentistry, Universiti Malaya, Kuala Lumpur 50603, Malaysia
2. Faculty of Dentistry, Universiti Malaya, Kuala Lumpur 50603, Malaysia
Publication Type:Journal Article
Keywords: Orthognathic, decompensation, Class III malocclusion, lower incisor angle, Li-APo, prediction
From: Annals of Dentistry 2021;28(1):15-22
CountryMalaysia
Language:English
Abstract: The amount of incisor decompensation during pre-surgical orthodontics may affect the outcome of Class III orthognathic cases. The purpose of this study was to assess the lower incisor changes post-orthodontic decompensation in Class III surgical cases and to investigate the amount of crowding as a predictive factor. This was a retrospective study reporting on 22 Class III orthognathic cases. The lower incisor angulation (LIA) and distance of the lower incisor edge to the A-Pogonion line (Li-APo) were measured on pre-treatment and presurgical lateral cephalograms whereas crowding was measured on digitised pre-treatment study models. Pearson’s correlation (p <0.05) was used to assess the correlation of crowding with LIA and Li-APo changes, and prediction of the lower incisor decompensation was conducted using linear regression analysis. Results showed lower incisors were retroclined at 79.84° ± 7.08° and positioned ahead of APo line by 6.52 mm ± 2.97 mm at the start of treatment. Pre-surgical LIA and Li-APo were found to increase following orthodontic decompensation to 90.43° ± 5.96° and 10.34 mm ± 3.25 mm, respectively. There was a moderate positive correlation (r = 0.592) between crowding and Li-APo changes which was statistically significant, p value = 0.004, and had a strong predictor with 31.8% predictability. However, LIA showed a weak correlation (r = 0.329) with crowding and was not statistically significant (p = 0.135). Li-APo changes during orthodontic decompensation can be predicted with 31.8% predictability using the formula; Li-APo change = 2.064 + 0.503 (crowding).
Full text:9.2021my0138.pdf